The not-so-mobile Byron Leftwich will be on the sideline for a third consecutive week with an ankle injury that's about 90 percent healthy. His replacement, David Garrard, offers more mobility than Leftwich, and that's what Jaguars coach Jack Del Rio is looking for.

Credit Leftwich for being professional in how he's handled the situation, but face it, he knows and we all know he's been benched. In a different manner, Drew Bledsoe lost his job in Dallas because sacks and interceptions were mounting and Tony Romo offered a way to escape from those disasters.

It promotes an interesting question: Has the age of the pocket passing quarterback ended? Is the trend to have a league of mobile quarterbacks and moving pockets?

Although that may be on the minds of coaches and general managers who have the opportunity to upgrade speed and mobility at the position, the answer is no. First of all, there aren't enough good running quarterbacks to successfully fill 32 starting lineups.

Plus, look at the NFL stats. The six highest-rated quarterbacks in the NFL are pocket passers. Peyton Manning, Damon Huard, Marc Bulger, Donovan McNabb, Philip Rivers and Drew Brees win games with their arms, not their feet. Though McNabb entered the league as a quarterback who could run, age and experience have settled him into more of a pocket passer who can occasionally break out of the pocket for a first-down scamper.

Even though pocket passers still dominate the QB landscape, coaches are showing a profound fear of sacks. If sacks lead to fumbles, coaches go berserk.

That's why I find the benchings of Bledsoe and Leftwich so fascinating. Although it's true too much credit and too much criticism go to the quarterback, I consider it dangerous to discard talented quarterbacks. Though Bill Parcells has looked correct after two games with Romo under center, I still view the move as a mistake that could leave the Cowboys a game short of the playoffs.

Bledsoe has his flaws. He's a sack magnet. He was sacked 16 times in the 185 times he dropped back from center, and his stats didn't look good. He completed only 53.3 percent of his passes, had eight interceptions and a 69.2 quarterback rating. In two and a half games, Romo has completed 64.6 percent of his passes and has a 93.7 quarterback rating. But he's also been sacked six times and has four interceptions.

AP Photo/Michael ConroyByron Leftwich will likely find himself on the trade market after this season.

The stat that still sticks out in my mind in favor of keeping Bledsoe at quarterback is 28.2 points a game. Somehow, someway, Bledsoe produces touchdowns. Obviously, the offensive line was a problem because opponents had no trouble rushing the middle of the blocking scheme and bringing Bledsoe down, but he had the ability to survive those hits and make plays.

That same offensive line could be the downfall of Romo. In most of his seasons, Bledsoe had the ability to put up between 20 and 28 touchdown passes, and there aren't a lot of quarterbacks who can do that. Diminished mobility might have made Bledsoe a quarterback who can no longer take a team to 11 or 12 wins, but I don't see Romo in his inexperienced state being able to do that either.

The Bills went 9-7 in 2004 with Bledsoe at the helm. That wasn't good enough. Bledsoe completed only 56.9 percent of his passes. He was sacked 37 times. But he threw 20 touchdown passes and the Bills were always a threat to score. The Bills dumped him. They've been 8-16 since then.

Since being the seventh pick of the 2003 draft, Leftwich turned around the fortunes of the Jaguars. They went from 5-11 the year he was drafted to 9-7 in 2004 and 12-4 last year. The Jaguars were 3-2 this season until both Leftwich and Del Rio miscalculated the QB's mobility on a swollen ankle and lost to the Texans, 27-7. That bad game cost Leftwich his job and probably his career in Jacksonville.

Maybe Leftwich won't be as great as Tom Brady or Peyton Manning. Like Bledsoe, Leftwich has flaws. He doesn't have the ability to escape sacks in the pocket. Unlike Bledsoe, he tends to get injured. But when he's out there, he is productive. He's good for 15 to 20 touchdown passes a year and doesn't throw many interceptions.

But he's a pocket passer who's not at the top, so he's considered replaceable. For the past couple of years, Garrard has been one of the top backups in football. He's done a nice job in winning his two starts. But the problem with going with backups is they usually don't put teams over the top.

Sure, Huard came out of nowhere and has gone 5-2 as a starter. But Brad Johnson and Jon Kitna were considered two of the top backups in football last season. The Vikings went with Johnson and they are 4-4. Kitna will probably break a lot of Lions passing records this year, but the team is 2-6.

In other words, changing quarterbacks isn't the complete answer. The problems that sacked the starter should eventually befuddle the backup. And often, more problems surface after the change has been made.

You can see what's going to happen in Jacksonville. With Garrard at the helm, the Jags will be in the playoff race until the end, even though their defense has been handcuffed by injuries. They lost linebacker Mike Peterson and defensive end Reggie Hayward for the season. Defensive tackle Marcus Stroud has missed more than half the season with an ankle injury.

Chances are the Jaguars might not even make the playoffs, but they are in the hunt. Unless Garrard flops, Del Rio won't go back to Leftwich, and that will probably put him on the trade market next season. He has a $5.2 million salary and is entering the final year of his contract.

If Garrard finishes the season, Leftwich isn't going to want to be there. The Jaguars are going to have no choice but to trade him and try to sign Garrard to a long-term deal even though he's under contract.

That's a shame. The Jaguars drafted Leftwich following two 6-10 seasons and within two years, they were a playoff contender. He has a 24-20 record. Players believe in him. He's a winner and he's only going to get better.

Maybe he never will be on the same level as Brady, Manning, Carson Palmer and the latest budding star, Rivers, but he's good enough to be sixth or seventh in the Pro Bowl considerations. He's a success. But the Jaguars want more.

It seems as though Leftwich and Bledsoe were tagged as statues in a league that wants quarterbacks who can move. But if you look at the stats, pocket passers aren't going away. They are still at the top of the statistical charts. Quarterbacks are quarterbacks. They are the most important players on the roster.

Though he hasn't been flashy, Steve McNair has done exactly what was expected when he went to Baltimore. He's helped the Ravens get off to a 6-2 start and a two-game lead in the AFC North. McNair's lost a lot of his mobility. He's pretty much a pocket passer at this stage of his career.

It's good for the league for guys like Romo and Garrard to surface and become productive quarterbacks. Leftwich can go somewhere else and resolve another team's quarterback needs. As for Bledsoe, he may not want to move. He's talked about retiring if he has to enter a backup phase of his career. That's a shame.